A domestically manufactured nuclear reactor coolant pump (hereinafter, nuclear reactor coolant pump) includes a standstill seal device in addition to a general three-stage seal of the nuclear reactor coolant pump to prevent a coolant from leaking when a loss-of-coolant accident (LOCA) occurs in a nuclear power plant. The standstill seal is a device positioned above the three-stage seal and configured to prevent the coolant from leaking using a pressure generated by supplying nitrogen to inside of a seal housing, but a power source is surely needed for supplying the nitrogen.
This is because a nitrogen injection system is currently classified as a non-safety system, and when an accident in which power is not supplied, e.g., loss-of-offsite-power (LOOP) and station blackout (SBO), occurs, coolant leak prevention by injecting the nitrogen may not actually be possible.
In Japanese Laid-open Patent Application No. 1996-334586 (NUCLEAR REACTOR DEVICE AND OPERATING METHOD OF SAME), although a gas reaction suppressor, which receives an accident occurrence signal and injects nitrogen for suppressing reaction between hydrogen and oxygen generated when such an accident occurs at a nuclear reactor, is disclosed, a nitrogen injection system is classified as the non-safety system as described above. Accordingly, the above-described device uses a method of supplying nitrogen using power, and there is a problem in that the nitrogen may not be supplied when the power is not supplied.